New research from BC Children’s Hospital Research Institute, published in Cell Reports Medicine, finds that breastfeeding can benefit children’s health well into childhood, especially for families of lower socioeconomic status (SES).
Children from lower-SES families face a higher risk of chronic disease, which can increase financial strain over time and reinforce existing inequities across generations.
“Socioeconomic status isn’t biological, but its effects on the body certainly are,” says Dr. Stuart Turvey, co-senior study author, investigator at BC Children’s Hospital Research Institute (BCCHR) and professor of Pediatrics at the University of British Columbia. “We wanted to understand how differences in early-life conditions shape children’s health, and how we might interrupt that cycle.”
A large part of Dr. Turvey’s research has focussed on how the composition of bacteria and other microscopic organisms that reside in the gut can affect our health especially for those of children.
Socioeconomic status isn’t biological, but its effects on the body certainly are.
– Dr. Stuart Turvey
In this study, the team examined dozens of factors between pregnancy and early infancy that influence the infant gut microbiota and chronic disease by using data from the CHILD Cohort Study. The CHILD Study is the largest birth cohort study in Canada that has followed participants from mid-pregnancy into childhood and adolescence.
In the study, families with a higher SES demonstrated broad differences from other families, including the composition of the infant gut microbiota, and had a lower risk of asthma, obesity, and behavioural challenges at age five.
When comparing these differences, breastfeeding stood out as a key mediator influencing the effect of SES on infant development. Breastfeeding was shown to protect the infant microbiota well into early childhood, and was associated with a reduced risk of chronic disease at age five. The protective effects of breastfeeding were especially strong among children from lower-SES families. A similar finding was found in an independent Danish cohort, Danish COPSAC2010, suggesting that these results are not unique to Canadian families.
“What surprised us was how consistent the effect was,” said Dr. Darlene Dai, lead author and biostatistician at BCCHR. “Breastfeeding seemed to act as a shield, protecting the infant microbiota across many different exposures. That protection may be especially important for children facing higher-risk early-life conditions.”
These findings underscore the need for stronger support systems that give all families access to these protective effects — even in countries like Canada and Denmark, where parental leave policies are relatively generous. “We were surprised by how much breastfeeding made an impact, even among Canadian families,” said Dr. Turvey. “It suggests that even with parental leave in place, families are still facing real pressures, and that more support could make a meaningful difference.”
Breastfeeding seemed to act as a shield, protecting the infant microbiota across many different exposures. That protection may be especially important for children facing higher-risk early-life conditions.
– Darlene Dai
The researchers note that breastfeeding may be only part of the story. Infant microbiota development also depends on exposure to beneficial bacteria in the surrounding environment. “As infants, we don’t just get microbes from our mothers. We also acquire them from the world around us,” said Dr. Charisse Petersen, research associate at BCCHR and co-senior author. “If those beneficial species are disappearing from our communities, babies may not have the microbes they need to fully benefit from breastmilk.”
One species that stood out was Bifidobacterium infantis, a bacterium historically well adapted to the infant gut but now thought to be less common in industrialized countries. It is particularly efficient at metabolizing breastmilk and supporting infant health. “B. infantis is really a microbial powerhouse,” said Dr. Dai. “It can do a remarkable amount on its own. Without it, it takes many more kinds of beneficial bacteria to get the same benefits.”
As infants, we don’t just get microbes from our mothers. We also acquire them from the world around us,
– Dr. Charisse Petersen
In this study, B. infantis was protective against three of the four chronic disease-related outcomes examined — yet its levels were consistently lower than other Bifidobacterium species across all CHILD Cohort Study locations. Together, these findings highlight the potential value of reintroducing this species into early-life environments where it may now be too low or missing.
Taken together, the findings suggest that the benefits of breastfeeding are shaped not only by individual choice, but also by the social and structural conditions that make breastfeeding more or less possible. The researchers emphasize that these findings are aimed not at families already navigating complex social and economic pressures, but at the systems that shape what is possible for them.
“We often try to leave families with clear, positive actions they can take. This paper is different. The real message is that socioeconomic conditions shape what’s possible for families. That makes this a policy conversation.”
Dr. Charisse Petersen
By identifying breastfeeding and beneficial microbes as pathways that may help buffer the effects of socioeconomic disadvantage, the researchers hope these findings will help inform policies and supports that give more children a healthier start in life.
